A microchip laser using a solid laser realizes miniaturization of a light source. The microchip laser is a solid laser crystal to be pumped by a semiconductor laser, and a resonator length thereof is reduced to about several millimeters.
Generally, output stability is enhanced by reducing the resonator length of the solid laser crystal (refer to Non-patent Document 1). Further, the microchip laser is combined with a wavelength conversion element to generate green light (refer to Non-patent Document 2).
Patent Document 1 discloses a semiconductor laser device in which a semiconductor laser array, a solid laser crystal, and a non-linear crystal are combined to perform high-power output of green light.
Further, Patent Document 2 discloses a laser light source which is aimed at increasing the output power by arranging solid laser crystals in a two-dimensional array.
Furthermore, Patent Document 3 proposes a method of making pump light emitted from a semiconductor laser incident on a solid laser crystal without using a lens by disposing the solid laser crystal close to the semiconductor laser, thereby to realize miniaturization of a laser light source.
Moreover, Patent Document 4 proposes a method of miniaturizing a laser light source and constituting an SHG laser of an internal resonator structure by reducing the resonator length according to Nd concentration in a YVO4 crystal.
In addition, Patent Document 5 discloses a method of pumping one laser crystal with plural semiconductor lasers to achieve high output power, and a method of pumping plural laser crystals which are bonded together, with plural semiconductor lasers.
A laser light source disclosed in Patent Document 6 is proposed as one for realizing further miniaturization of a green light source and higher output power. The laser light source disclosed in Patent Document 6 adopts KTiOPO4(KTP) as a non-linear optical crystal and YVO4 as a laser crystal, and these crystals are bonded together using an adhesive agent.
Patent Document 1: Japanese Published Patent Application No. 2004-111542
Patent Document 2: Japanese Published Patent Application No. Hei.9-246648
Patent Document 3: Japanese Patent No. 2586200
Patent Document 4: Japanese Patent No. 3091329
Patent Document 5: Japanese Patent No. 3053273
Patent Document 6: Japanese Published Patent Application No. 2004-31683
Non-patent Document 1: Journal of Optical Society of America B Vol. 11, pp 436-445, 1994
Non-patent Document 2: Optics Communications 105 (1994) p 183-187